Automatic telephone system



Sept. 2l 1926. A

. R. F. STEHLIK AUTOMATIC TELEPHONE SYSTEM Filed March 19, 192s is linked with the inder F by Yand effective arrangement Ii'r, or.CnICAGo, ILLINoIs, AssreNoR, isY

`PATENT oFrlcE."

Masai: Assrcuivmuas,

'rofAU'roMATIC ELECTRC INC., or CHICAGO, iLLINors', A Conrona'rrou or DELA- WARE.

AUTOMATIC TELEPHONE SYSTEM..

.application mea March 19, 17923. seriai No. 625,997.

and test or switching relays are replaced by a single relay that ydoes ,the work of both.

Another object is the provision ota simple l for restarting a the terminals of a the accidental rethe test contact finder in case it stops on non-calling line due to moval of ground from thereof. A n

Still another object isto provide suitable circuit arrangements forgca'usinga second finder to find a calling line in Acase the rst .to find such line is unable to establish a hold-` ing circuit for itself.

Such other` features as are notmentioned here will appear Yiully and be described dur-y ing the course of this specification.

Referring now to the accompanying drawing, there is shown' by means of the usual circuit diagrams a sufficient amounty of apparatus in a telephone system embodying the principles ofthe invention to enable the invention toI be understood.

A telephone line is shown extending from the substation A to the exchange lwhere it vterminates in the banks of agroup cilinder switches suchr as the inder F, and has associated with `it the linejcircuit LC. This drawing shows 'also the iinder allotter FA, which extends the starting circuit yto an idle finder after the allotted one is taken for use. The drawings show also the selector E' which the conductors 7 5-7 7, inclusive.

The substationY A is an automatic substation, and is, therefore', provided with a calling'device in addition to the other usual, and well known instrument'alities. Each of the inders such as the finder F, together with the' finder allotter FA, is mechanically ofthe well known rotary type ot switch'in which the wipers haveV no normal position and are advanced in a forward direction only by the stepping magnet, and in which the wipers are 'advanced when the ,common alarm buzzer trom operating irl-response to the en- Vergization o-relay 30 which occurs at thisV time.

stepping magnet deenergizes rather than when the stepping magnetenergizes. l Y H The selector E is an automaticnswitchcf the usual vertical androtary type of which the bank -contacts are arranged in horizontal rows orv levels. .Y f f Y, j g l 'In order to explain the detailed operation of the equipment shown, itV will be assumed that the subscriber at substation A desires to make a call and, accordingly, removes his receiver from the Vswitch-hook.

l/Vhen the receiver is removed lat substationA, a circuit is closed over line conductors 11 and 12 for the v upper winding of the combined line and cut-off relay 14. Owing "i tothe resistance 15, which is included inthis circuit, the relay 14 energizes only.' sutliciently to operate the armatures `17 and 1 9. Armature 17, vupon being attracted, disconnects test Contact 22 from ground and connects it to the private normal conductor 13,

and armature 19, upon being attracted,v

places ground on start wire 29, thereby closingl a circuit for the lower winding of the combined start and test-or switching relay 63 oi' the finder- F as follows: From ground by way of armature 18,03 relay.v 14 and its resting Contact, working Contact of armature 19`and said armature, start conductor 29, series signalrelay 31, armature 42 and its resting Contact, wiper 46, conductor 50, resting Contact oi armature 72 and said armature, and the lower winding of the marginally adjusted relay 63 to battery. Relaysand 311 energize in series over this circuit, and f relay 3 1 opens a point in the circuitot the buzzer 35 to prevent said Owing to the fact that the current through the lower winding of Yrelay 68 is limited by thehigh resistance series relay 31 inthe finder allotter FA, relay 63y energizes only su'liiciently to operate armatures 70 and 71. Armature 71, upon being attracted, closes a circuitvfor the upperwinding of relay 63 From ground by way ofwiper 44 of the allotter FA, conductorf48,.armature 71 and its 'working contact, upper Winding of relay 63, Linterrupter contacts 64 and stepping magnet 61 to battery. Armature^70, uponbeing attracted, connects test wiper 25 to the junction of the upper or test winding of rein series with stepping magnet 61 as follows:

lay 63 and stepping'magnet 61. The further operation of the finder F depends upon whether the'wipers 24-26, inclusive, of the finder F are standing upon a calling or noncalling line. In case the wipers of the finder are standing upon the terminals of a calling Y line, test wiper 25 is in engagement with an ungrounded test contact and the operation of armature is without etect, and the upper winding of switching relay 63 becomes energized immediately with the result that case, the upper winding of relay 63 is short Vcircuited and does not become energized. ln

this case, the groundk potential encountered by test wiper 25 isextended through armature 70 and its working Contact, and interrupter contacts 64- to stepping magnet 61. By the operation of stepping magnet 61 over` this circuit, the wipers 24-26, inclusive, are rotated step by step owing to the buzzer-like action of said magnet 61' occasioned by the interrupter contacts 6a.

When the wipers 24-26, inclusive, of the finder F arrive upon the terminals 21-25, inclusive, of the calling` line, test wiperA 25 engages the ungrounded test contact 22 and the stepping movement of the finder accordingly ceases. Vihen this occurs, the previously tracedcircuit through the upper winding 'or' relay 63 becomes effective, whereupon relal 63 enerfrizes full f thereb attractino' the t i Y n remaining armatures. Upon the complete jenergization of relay 63, thefline conductors Vare connected through 'at armatures 63'aiid 74; a local circuit is closed for stepping magnet 61 at armature 73.; the lower winding of relay 63 is shifted from start conductor 50 to the release trunk conductor 76 at armature 72; and at armature 69 test wiper 25 is disconnected from the junction of the upper winding of relay 63 and stepping magnet 61, and connected to. the upper winding of the special test relay 62 by way of armature 65 and its resting contact. rlhe armature of relay 62 is lightly adjusted,

Yand'this relay accordingly energizes quic ly in series with the lower orcutoii' winding of relay 1li over the following circuit: .From ground by way ol the upper winding of relay 62, resting contact of armature 65 and said armature, workingcontact ot ar- Amature 69 and said armature, test Vwiper 25,

test contact 22, armature 17 and its working contact, and the lower winding ot relay 14 to battery. Upon energizing over the above trunl: conductor 76.

the banks ci theconnector switches having raced circuit, relay 62 closes a locking circuit ifor its lower winding at armature 66, which includes the worlring contact of armature 73'and said armature, and at armature 67 opens the circuit of stepping magnet 6l before said stepping magnet has had time to energize, and closes a circuit for relay 32 of the linder allotter FA, which will be desei 'bed later.r lt may be pointed out that, whereas the stepping magnet 61 has a coniparatively heavy armature and a stiff ad justmcnt, the relay 62 has a lighter' arniature and a less stilij adjustment, and for that reason is able to energize and open the circuit ofv stepping magnet 61, as above pointed out, beiore stepping magnet 61 can operate. The above mentioned circuit for relay of the iinder allotterv Frilisas follows: From `ground by way of the working contact ot armatur 73 and said armature, armature 6"? and its worfing contact, conductor 49, wiper 45, armature l1 and its resting contact, and relay 32 to battery. .Relay 32 does not energize immediately upon the closure oi this circuit owingto the tact that its core has aV copper collar placed on the armature end thereof as is indicated by the biaclr upper portion of the core.

is a further result of the energization of the special test relay 62, test wiper 25 is disconnected :from the Vupper winding orl relay 62 (leaving relay 62 looked up over its lower winding) and extended to release is a result `ot the line conductors of the calling line being connected up at armatures and M or relay 63, as pointed out above,

kline relay 135 ofatlie selector "Efenergizes over the calling'sub'scribersline andcloses a circuit for release relay- 136 atar-mature 151. Release relay. 136, upon energizing, opens a point in the circuit of release magnot 14A and prepares a circuit for vertical magnet 141:0 at armature 153. and at armature 152 applies ground to the release trunk conductor .7 6. This ground potential extends by way of the working contactpof armature 7 2 and said armature to the lower winding oi" relay 63, thereby completing a holding circuit tor this relay. The ground potential applied to release trunk conductor 6 extends also by way oic the Yworking contact of armature 65 and said armature, and thence by way of the previously traced circuit to battery through the lower winding ot ...e-lay 14.-. Relay 14- now energizes suiii- Y cuit et the lower winding of relay lll` YeX- tends by way ot the private normal conducto multiply connected test contacts in 76 ott the selector E, a. circuit is Y magnet 84zis operated ,in

teodsz eases' te the use @feststellen thereby 'gt'iardimgrv said line againstintrus'ion 1n the usual manner.

, a further result ot the ground potential being applied to release trunk conductor closed tor the uppeerl winding of relay 88 ot the finder allotter FA through conductor 47 and test Wiper 48. Relay 88,v upon energizing, opens the circuit of relay at armature `41 before said relay 82 has had time to energize, and at aimature 42 opens the starting circuit so as to prevent interference wi-th the finders pass'e'dvover by the wiper 46, which is subsequently rotated. A branch ot the circuit of the upper winding of relay 88 extends by way of interrup'ter contacts 40to stepping magnet 84',A and accordingly the stepping the manner ot a buzzer with the result that the wipers 48L46, inclusive, are opera-ted step by step in search Otan idle iinder. The wipers otthe finder allottedi stop' upon the next idle iinder being reached owing to the absence ot a ground potential on the test Contact thereof, and relay., 88 accordingly deenergizes.

t will be noted that wiper 44, on moving y ott the bank Contact 48, opens the circuit ot l nb alga the upper winding ot the two-step relay 681. This lea-ves relay 68 locked upby means ot its lower winding which is energized from the release trun'lr conductor 76 through ,the

`working Contact ot armature 72 rand said armature. This winding, although unable toene'rgize the relay suiiicie'ntly to operate all theaifiriatues when its circuit is closed through the high resistance series relay 81 of the yfinder allotter FA, is now energized through a` circuit which does' not include the high resistance relay 81 and for thatY reason easily maintains the relay operated just like any` ordinary relay winding. Y

llhen the calling subscriber operates lhis eallig' device in accordance with the first in the desirednumber, the circuit ot line relay 185 (switch E) is opened a corre'- sponding number ot times. relay 185 deenergizes in'response to one of the interruptions thereby produced', it closes a;circuit for vertical magnet 140 as follows:

From ground by way ot the resting contact otarmature 159 and saidA armature, armature 151 and its resting Contact, armature 158 and its working rContact,relay 187, and vertical magnet1'40' to battery. Bythe operation ofy kvertical magnetr140', the wipers 161-168, inclusive, are raised opposite the desired level ot b'a'nl'r contacts. Relay 187 is energizedin ,series with vertical magnet 140 and, being slow-acting'.A retains vits armature attracted throughout the vert-ical movement. As a result of the en'ergization 01" relay 187,

itcloses` a circuit at arn'iaturep154 vtor stepping relay18'8 by way ot oli normal contacts 148` (which close upon' the first vertical step)v Each time line y prior to the d'eenergiz tacts inthe selected level, and, near the end of its stroke, opens the circuit ot-stepping relay 188 at'interrupter contacts 142. Step'- ,i ping relay 188, upon de energizing, opens the circuit ot rotary magnet 141vv at armature 156, whereupon rota-ry magnet 141r deenergizes also and closes its interrupter contacts 142 again. In case the trunk terminating 1,. in the lirst set ot bank contacts is idle, switching relay 189 energize; immediately. Assuming rthe trunk to be b-usy,= however, switching relay 189 is short-circuited by the ground potential encounteredby test wiper 162, and stepping relay 188 energize's fromv this same ground potential and closesy the circuit'ot rotary magnet 141 again, whereupon the switch wipers'` are rotated into engagement with the-next set ot bank 'contacts rhis alternate operation of stepping lrelay 188 and rotary magnet 141 continues untillan idle trunk is reached, which trunk it will be assun'ied is the one termina-ting in bank contacts 164'166,"inclusive, wheregizing, opens a pointin the test circuit and prepares the holding circuit at' armature y 158; disconnects ground trom armature 151 ot linegrelay 185 atvarma'tlure 1 59, thereby opening the circuit ot release relay186'; and at armatures l157 and MSO-disconnects conductors 75 77 trom the windings ot line A relay 185, andv extends them by way of wipers 161 and 168 and'banl: contact-s 164 and 168 to the windings ot the line relayv (not shown)V ot lthe' switch to which the seized trunk extends. Holding-ground is now suppliedl by way ot there'l'ease trunk conductor ot the seized switch through test Contact 165, test wiper 162,and armature 158 and its working' Contact to" release trunkconductor 7 This ground pot-eutial is supplied A.on et the slow-acting release-inlay 186' serves to maintain the operated 'switches in their respectivefoperated positions. Y

The callingsubscriber now dials the' re mailling digits in the desired number with the result thatthe connection is completed in the well-known inanne'rA and,` when he vrelay 189. Switching relay 189, upon ener- Y ing of relay 14 is not connected up and noY replaces his receiver, after having either completed the desired connection or abandoned the call, the ground potential is removed from the release trunk conductor T6 by the switch to which the connection has been extended and relays 14, 63, and '139 accordingly deenergize.v The deenergization of switching relay 139 of the selector E results in the circuit of release magnet 144 being closed at armature 159, whereupon the said release magnet 144 energizes and the switch wipers are restored to normal position in the usual manner, whereupon the circuit kof release magnet 144 is opened at the off normal contacts 145.

The deenergization of the combined line and cut-ott' relay 14 of thercalling linerrestores the associated circuits to normal, and

the deenergization of the relay 63 of the finder F results in' the associated circuits being restored to their normal condition, and the circuit'of the -lower winding of relay 62 is opened at armature 73, whereupon relay 62 deenergizes. rllhe entire connection is now released and the apparatus involved is in readiness to be used in a subsequent call.

In order to explain how a inder switch such as the finder F, for example, is restarted after having stopped on a non-call` ing line, it will be assumed that the start wire 2.9 is grounded due to some line other 'than the line of substation A calling. lt will be assumed further that the finder al lotter is in the position shown in the drawing and, consequently, that the finder F is started in search of the calling line. A still further assumption that will be made at this time is that the wipers 524-26, inclusive, of

the finder F reach the terminals of the line of substation A before they reach the terminals of the calling line and that armature V17 of relay 14 is'either not properly adjusted .or else the resting contact thereof is covered with dust or some other insulating` material. That being the case, the test contact 22 is ungrounded and the finder F accordingly stops on the terminals 21-23, in-

clusive, and the two-step. relay k63 energizes completely. In this case, since armature 17 of relay 14 is not attracted, the lower windcircuit is closed for the upper winding of the special test relay 62. Under these conditions the test relay 62remains deenergized and the circuit of stepping magnet 61 through the working contact of armature Y73, armature 67 and its resting contact, and

the resistance 64 remains closed sufficiently long to permit stepping magnettl to energize. Upon energizing, stepping magnet 61 opens its interrupter contacts in the usual manner, with the result that the circuit oi" the upper winding of relay 63 is opened and ysaid' relay 63 deenergizes and opens the cir- Y cuit of stepping magnet 61 at armature 73,

whereupon stepping magnet 61 deenergizes also. Due to the energization and deenergization of stepping magnet 61, the switch wipers 24-26, inclusive, arel stepped to the nei-Tt setvof contacts and, irponfrelay.v 63

again energizing part way overvits lower "F by the release relay136 of thersfelector E..

1t may happen at rare interra-ls that one of the three conductors of the trunk extending between the i'inderrF and thev selector E may be open, with the result either that theV line relay 135 does not energize lor that the energization of linerelay 135 is ineiiectiveY to cause the release trunk conductor 76 to be grounded. In this case the usual circuit for stepping magnet 84 is not closed through p wiper 43 and the slow to energize relay 82 is able to energize over its previously tracedk circuit which includes the vattracted armatures 73 and 6'? and armature 41 andits resting contact. Upon energizing, relay 32 closes a circuit for stepping magnet 34 atl Varmadture 38, whereupon stepping magnet` 34 energizes and lmoves the associated pawl into engagement with the next notch in the wiper driving ratchet wheel, but owing to.

the fact that its wipersare advanced upon the deenergization rather than its energizae; Y

tion, it does not move the associated'wipers. As a further result of the energization of relay 32, it closes'a circuit for relay 831`at armature 89, whereupon relay 33 energizes and opens the circuit of relay 32 at armature 41, whereupon relay 32' Vd'eenergizes and opens the circuit of stepping magnet 34, with the result that .stepping magnet 84 deenergizes and advances the wipers '4S-46, inclusive, into engagement withy theY terminalsof the next finder.` ln the iinderrF, relay 63` deenergizes in response to the wiper 44 moving on" bank Contact 48, owing to the fact that no holding circuit for the lower winding hasV been vclosed over release trunk conductor 76. Tl is results in the conditions in the finder F Ybeing restored to normal. j Y u Since the start conductor 29 is 'still grounded owing tothe fact that the twooccasionall ha anens that the, startinff i Y e a relay in said finder having contact` springs and an armature for actuating them, means responsive to a call for causing said relay to partially operate its armature to close anY operating circuit through certain of said springs, and means for causingsaid relay to fully operate its armaturewhen the calling line is foundV to stop the nder and complete the connection to such calling line through certain other of said springs.

11. In va finder'switch, a combined start, stop and switchingrelay having only two stages of Operation, an operating circuit closed only in the first stage, and talking con-ductors closed only in the'second stage.

12. In a finder switch,"a relay having a core and armature, contact springs directly actuated by said armature, means for operating said armature part way to close an operating circuit for the finder through certain of said springs, and means for fully operating said armature to open said operating circuit at certain other of said springs.

13. In a finder switch, a marginal two step relay, and an operating circuit for said linder completed on the first step and only opened on the second.

v 14. In a finder switch having wipers, a ydouble wound relay, a starting circuit including'onevwinding of said relay, and a test circuit including the other winding and a wiper ofthe switch. f

15. In a telephone system, a finder switch means for starting said switch in search of a calling line, a relay energized when the finder is stopped, whether the calling line has been reached or'not, a restarting circuit vclosed by said relay, a test relay for testing the line on which the fin-der has stopped, and means controlled by said test relay for opening said'restarting circuit if the line tested is the calling line.

15. In a telephone system, a finder switch, means for starting said switch in search of a calling line, a relay energized when the finder is stopped, whether the calling line has'been reached or not, a restarting circuit closed by said relay, a test circuit also closed by said relay, a relay in'said test circuit for testing the line on which the finder has stopped, said test relay being energized if the finder has stopped on the calling` line, and meanscontr'olled by said testrelay for opening said restarting circuit.

. 17. In a telephone system, a group of finders, an allotter having a plurality o-f wipers for selecting idle finders,'a magnet, two circuits for operating said magnet to advance said allotter, each circuit including a wiper of the said allotter, and means for rendering one circuit effective only when the other is ineffective. Y

18. In a telephone system, a group of. finders, an allotter for pre-selecting an 'idle finder, a circuitfor starting the pre-selected finder responsive to a call, means responsive to the completion of the connection with the calling line for advancing said allotter to select another finder, and other means for causing' the advance of said allot-ter respon` causing the advance of said` allotter effective only in case the said first meansfails toV` accoinplish the advance of the allotter withina pre-determined time.

20. In a telephone system, a finder switch,`

a starting circuit having two branches, one branch including a start relay for said finder, a second relay included in said first branch in series with said start relay, athird relay included in the second branch, and a signal controlled third relays.

21. In a telephone system, a finder switch, a start relay and circuittherefor, a signal and a circuit therefor, means for closing both circuits, and means controlled over the start i cuit.

Ya start relay and circuit therefor, a signal and circuit therefor, means forl closing the start circuit, means responsive to such clos-` ure for closing the signalling circuit, and

means responsive only in case the start circuit is intact throughoutv for .opening the lines, a trunk line, a finder switch for eX-V tending a calling-fone of saidy linesto said trunk line, a combinedstarting and stopping relay in said finder, a circuit controlled4 by the calling subscriber for partially operating said relay to cause it to perform its starting function, and another circuitv completed when the calling line is found for fully operating said relay tocause it to perform its stopping function.

In witness whereof, I hereunto. subscribe my name this 15th day ofMarch, A. D.,

RUDOLPH F. STEHLIK.

jointly by said second and circuit for opening the signalling cir;

In a telephone system, a finder switch, i

los 

